Officials have found the cause of the norovirus outbreak at Pioneer Primary School in Singapore. On Thursday, they found the cause was unsanitary preparation of foods and sharing of toilet facilities.

Six students were found positive with the norovirus after examination of stool samples.

The Health Ministry of Singapore said sloppy hygiene practices in preparing foods by food handlers who were infected with norovirus and the fact that workers, students and staff all shared the school public toilets contributed to the spread of the infection.

According to a July report, 147 people have been affected by norovirus gastroenteritis cases, including students, staff and food handlers from the school.

The ministry has advised the school and the six food handlers to take necessary precautions to prevent future outbreaks.

The health ministry said, "Noroviruses, which are highly contagious, are found in the stool or vomit of infected people and it's important to observe good hygiene always to avoid being infected."

The ministry added that those with symptoms of the viral gastroenteritis should not attend either school or work until they are cured.